That's me... And you can't refute what is fact. Making a habit of holding lithium ion batteries at their saturation voltage reduces their lifespan. Anyone telling you otherwise are the ones giving bad information.
Now, some devices limit their peak charge point, which, in turn, mitigates the degradation. But most current phones crank up the peak voltage up closer to the cells maximum safe charging limit in order to maximize the amount of stored charge... They figure you'll get rid of the thing before it degrades to the point of annoyance.
Oh, since everything has safety circuitry, leaving a fully charged phone in the charger won't cause a fault.. I.e. booms. But safety and longevity are two different things.
In fact, there are several laptop manufacturers that now include charging features that will allow the laptop to drain down to a much more gentle zone, only allowing the laptop to charge up 100% based on a schedule (such as if you expect to take it off the charger or dock every day at 9am).